The stellar content and distance of UGC 4483

• Published in: Monthly notices of the Royal Astronomical Society 2001-06, Vol.324 (1), p.249-256
• Main Authors: Dolphin, A. E., Makarova, L., Karachentsev, I. D., Karachentseva, V. E., Geisler, D., Grebel, E. K., Guhathakurta, P., Hodge, P. W., Sarajedini, A., Seitzer, P.
• Format: Article
• Language: English
• Subjects: galaxies: distances and redshifts; galaxies: individual: UGC 4483; galaxies: irregular; galaxies: stellar content
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1046/j.1365-8711.2001.04312.x

We present HST/WFPC2 observations of UGC 4483, an irregular galaxy in the M81/NGC 2403 complex. Stellar photometry was carried out with HSTphot, and is complete to V≃26.0 and I≃24.7. We measure the red giant branch tip at I=23.56±0.10, and calculate a distance modulus of μ0=27.53±0.12 (corresponding to a distance of 3.2±0.2 Mpc), placing UGC 4483 within the NGC 2403 subgroup. We were able to measure properties of a previously known young star cluster in UGC 4483, finding integrated magnitudes of V=18.66±0.21 and I=18.54±0.10 for the stellar contribution (integrated light minus Hα and [O iii] contribution), corresponding to an age of ∼10–15 Myr and an initial mass of ∼104 M⊙. This is consistent with the properties of the cluster's brightest stars, which were resolved in the data for the first time. Finally, a numerical analysis of the galaxy's stellar content yields a roughly constant star formation rate of 1.3×10−3 M⊙ yr−1 and mean metallicity of [Fe/H]=−1.3 dex from 15 Gyr ago to the present.